* {
    padding: 0;
    margin: 0;
}
li {
    list-style: none;
}
a {
    text-decoration: none;
    color: inherit;
}
/* 万能清浮动 */
.cl::after {
    content: "";
    display: block;
    clear: both;
    height: 0;
    overflow: hidden;
    visibility: hidden;
}
.f1 {
    float: left;
}
.f2 {
    float: right;
}
